WAC 296-835-11015. Take additional precautions if you recirculate ventilation system exhaust air into the workplace

IMPORTANT: This section applies if exhaust air from dipping or coating operations that use flammable liquids, or liquids with flashpoints greater than 199.4°F (93°C) is recirculated back into the work environment. (1) You must only recirculate air that contains no substance at a concentration that could pose a health or safety hazard to employees. (2) You must make sure any exhaust system that recirculates air into the workplace: (a) Passes the air through a device that removes contaminants; (b) Sounds an alarm and automatically shuts down the dip tank operation, if the vapor concentration of any substance in the exhaust air exceeds twenty-five percent of its LFL; (c) Monitors the concentration of vapor from flammable liquids or liquids with flashpoints greater than 199.4°F (93°C) with approved equipment. Note: 1. The LFL concentration in the air must be determined after the air passes through the air-cleaning device and before the air reenters the workspace. 2. Most substances will pose a health hazard at a concentration far below twenty-five percent of its LFL.